The present invention relates to a device for assisting in the navigation of a person, both inside and outside a building. The device, being fitted to the person, comprises at least: a computer (41) comprising in memory a digitized map of the place (1) in which the path of the person is planned between a departure point and an arrival point, and a location software; a human-machine interface linked to the computer; a set of sensors (42) worn by the person and linked to the computer, the sensors delivering information about the movements of the person; the location software performing a processing of the signals originating from the sensors (42) and from the interface, and performing the fusion of the data provided by the digitized map and the information arising from the sensors and from the interface, and then calculating on the basis of these data the absolute location of the person on the map and correcting the position estimation errors.